


Dumb Fish Boy and Leg Boy Get Yelled at By Fish Woman

by Polyhexian



Category: Invader Zim
Genre: Beach Day, Cryptid Hunting, Gen, Mer AU, ZADF, they're friends that annoy eachother!, they're in eighth grade, trans dib
Language: English
Status: Completed
Published: 2020-05-10
Updated: 2020-05-10
Packaged: 2021-03-02 22:00:35
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,081
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/24104053
Author URL: https://archiveofourown.org/users/Polyhexian/pseuds/Polyhexian
Summary: Zim and Dib go on a class trip to the beach and do some cryptid hunting. Mer au!
Relationships: Dib & Zim (Invader Zim)
Comments: 5
Kudos: 60





	Dumb Fish Boy and Leg Boy Get Yelled at By Fish Woman

**Author's Note:**

> Happy mermay!!! I was talking to my friend bri (hi bri!) Begging for prompts and they suggested mer au zadf and I was like lol sure I love fish. Let's DO this

"Didn't you bring a swimsuit anything?" Dib asked, adjusting the strap of his beach bag on his shoulder. 

Zim huffed, turning his lack-of-nose upward in the air. "Obviously not, land-boy. Zim will not be  _ swimming  _ in your filthy Earth ocean today." 

"The first time you have an excuse to actually go swimming and show off and you're not going to do it?" Dib raised an eyebrow, looking up at the bus waiting in the school parking lot and the rest of eighth grade classmates milling about, waiting to leave for their class beach trip in the early morning sun.

"As if Zim would be foolish enough to reveal himself in front of so many witnesses," Zim sneered, "You will not be getting your  _ alien proof _ today, Dib-stink."

"Oh, come off it," Dib twitched, rolling his eyes behind his glasses, "you know I'm not going to bother."

"You may be playing the long game with your ' _ friendship, _ ' Zim said, rolling the word like a swear, "but I will  _ not _ be letting my guard down. Zim is always prepared."

"If you really wanna miss out on the beach, sure," Dib shrugged, "Can't imagine you're going to have much fun sitting in your chair all day under the hot sun. 

"Zim will not be under the hot sun," Zim said primly, leaning over the side of his wheelchair to fiddle about in the bag slung over the handles, "I brought a parasol." He pulled out a delicate parasol the same pink as his invader uniform and opened it, giving it a quick twirl. 

"Well, I suppose that will keep you from burning like a crisp again," Dib mused, "But I brought you an extra bottle of sunscreen anyway, because I knew you would forget."

"You will give the lotion to Zim!" Zim yelled, "you will do this!"

Dub handed Zim the bottle, and he began immediately covering his scaly green skin in sunscreen like they were going to stop making the stuff.

"In any case," said Dib, pulling a waterproof disposable camera from his beach bag, "I Googled the part of the beach we're going to and there's totally reports of a Siren near there. I'm gonna try to find it!" 

Zim looked up, smearing lotion all over his face, "What is this 'Siren' the Dib speaks of?"

"It's like, a mythological creature," Dib explained, "It's like a mermaid, but evil. When they sing, it hypnotizes you so you have to go follow them, and they eat your brains or your liver or something. I guess they'd probably look like you, but less green."

Zim looked revolted, sticking out his tongue, "No earth creature could possibly match the magnificence of a Merken Invader," he sneered defensively. 

"Well, they have a fish tail like you, at least."

"Hmmph," Zim rolled his eyes. "So how do you propose you will resist this Siren's song, if it's so powerful, hm?"

"I brought earplugs!" Dib said, sounding confident, "It's always that simple in the stories."

"The Dib is going to get eaten for sure," Zim sighed, to apparently no one in particular.

The bus door opened and classmates started lining up to enter.

"Oh, hey, that's our cue," said Dib, "you  _ are _ coming then, yeah?"

"Of course Zim is coming," said Zim, folding his arms, "Leg-boy! Push my chair for me."

"Fine," Dib grumbled, "Bossy."

"Yes!" said Zim, triumphantly, as Dib grabbed the handles of his wheelchair and began to walk him towards the bus, "Zim is the boss of Dib and all humans, as it should be!"

"Uh huh," Dib consoled, as if to a small child.

* * *

"This area is uneven and impossible to navigate, could you have  _ possibly _ picked a more cumbersome path?" Zim spat, forcing his chair wheels over another crack in the flat rocks they were traversing. They had just gone far enough to lose sight of their classmates on the more populated part of the beach, but it would be easy to get back when they were done.

"You didn't have to come," Dib called back to him, "You  _ said _ you didn't want to come."

"I  _ don _ ' _ t _ want to come," Zim huffed, "But if you get killed on one of your little 'cryptid hunts' I will lose the satisfaction of defeating you myself. Besides, this creature is a denizen of the water, which is precisely my area of expertise."

"I thought you weren't going to get in the water," Dib snorted.

"I will not be," Zim fought with another break in the rocks, where it became craggy, and frowned, "Come back. You have to carry me."

"I'm not carrying you."

"You must!" Zim demanded, "your primitive Earth medical equipment cannot navigate this terrain!"

"You have hover jets in your dumb chair," Dib called back, stopping, because Zim really was falling behind, "There's no one here to see you, come on."

" _ Fine, _ " Zim moaned, and the wheels of his chair flipped sideways, picking itself up as he quickly scooted forward to catch up with the human.

"Was that so hard?" asked Dib, clambering up an incline.

"If I get dissected it will be your fault, and I  _ will _ return as one of your 'ghosts' to haunt you."

"That would be pretty cool."

"Ugh," groaned Zim, "You are incorrigible."

"Sure," agreed Dib, not sure what that meant. "Anyway, check it out. See this overhang? There's supposed to be a cave opening at the front and that's where the Siren lives."

Zim eyed the cliff face that jutted into the ocean with disdain, "You are going to get caught in a riptide."

"I'm not going to get caught in a riptide."

"You're definitely going to get caught in a riptide."

"I'm a good swimmer, come on! Cut me some slack. You're not even coming with me."

"Zim will be accompanying the Dib after all," said Zim, primly untucking his lap blanket that covered his fish tail and laying it on the back of his chair.

"Oh yeah? What changed your mind?"

"Nothing. Zim was simply lying earlier to keep you on your toes."

"Sure."

Zim wiggled his tail now that he could finally unfurl his fins correctly, unwrapping his ventral find from where they were tucked neatly beneath him. Then, without further ado, he flung himself onto the ground chest first and began wiggling toward the water.

"Aw, geez, come on, dude, fine," sighed Dib, setting his camera down to free his hands before he walked over and grabbed Zim around the sides, hefting him up and over his shoulder. Zim folded his arms triumphantly until Dib reached the edge of the water and tossed him in.

The alien dove quickly, enjoying the rush of water over his gills again and flaring out his neatly tucked fins, always kept uncomfortably hidden from the humans. He rose back up with a splash and leaned on the edge of the rapple where the water ended on his elbows.

"Coming, then?" 

"Coming," Dib said, kicking off his shoes and wriggling out of his shirt. Zim frowned.

"What's with the scars? I didn't give you those. At least, I don't think I have you those," Zim looked up in thought, tapping his chin with one claw, "Did I give you those?"

"What?" Dib startle-laughed, looking down at the top surgery scars on his chest, "Seriously? I was out of school for like a month. Were you not paying attention?"

"To Dib? Never," said Zim, sticking out his tongue, "Come. Zim will help your pathetic human body navigate the riptide."

"Cool."

Dib jumped unceremoniously into the water and Zim yelled, scrambling to dive before the wave knocked him over. Dib pulled himself back up to the surface, slicking back his wet hair out of his face. Zim poked his narrowed eyes above the water, glaring.

"Alright, fish boy, let's go check it out!" Dib said, excitedly, before driving back under water and kicking out away from the shore. Zim rolled his eyes and spun to speed off past him.

Beneath the surface, Zim inspected the currents. As he had predicted, the shallow water and sudden stop at the cliff made for prime riptide conditions, and he could see the way the water hit the seabed and crashed out to its sides chaotically, powerfully, tracking the motion of the water with his eyes. He knew better than to get anywhere near a current like that, and all it would do to  _ him _ was annoy him. Luckily, it was easy to map out a safe path toward the caves entrance when you were a superior water based life form and could see currents. He swam back up to the surface.

"You're almost certainly going to get sucked into a riptide and die," he said with a sniff as cold air hit his nostrils, and Dib flummoxed to tread water like the human scrub he was.

"Is there no way in without going through a current?" Dib grimaced, turning to look at the cave, "Hm."

"Not without my help," Zim grinned, flicking his tail in the water mischievously.

"Fine, whatever, so you want me to hold onto your back or what?" Dib said, frowning.

"Oh!" Zim blinked, having just anticipated making the human follow him, "Yes. You must. Zim is the only thing standing between you and certain death."

"Thanks," Dib said dryly, "C'mere."

He grabbed the Merkin's shoulders as tight as he could, trying to ignore how smarmy his ride was being about the whole thing. 

"Alright, so, let's- ah!" Dib barely had the presence of mind to take a deep gulp of air before his partner in crime dove under water again and swam rapidly through a twisting maze of dangerous currents, scrunching his eyes shut against the quickly moving salty water. 

He gasped for air, coughing and sputtering when they broke the surface again in the dark, immediately releasing Zim when he could feel craggy ground near his legs, clambering up to sit in knee deep water. 

"A little warning would have been nice!" He snapped.

"I'm sure it would have," Zim turned up his nose, before eyeing the shallow shelf and sighing, whirling up over it to sit down. "Though, I suppose you were- euch-  _ right _ . It's nice to go for a swim."

"What!" Dib gasped, "Don't tell me you're going soft on me now."

"I will kill you, Dib-worm."

"Well, it's pretty dark in here," said Dib, looking around, "Not that I can see much without my glasses, anyway."

"If you weren't going to be able to see anything in here, why did we even bother coming?" Zim scoffed, "How do you expect to tell the difference between me and one of your Sirens?"

"The Siren will probably complain less."

"Ha ha," Zim deadpanned, "The Great and Powerful Zim never complains about anything."

"Do you hear that?" asked Dib, suddenly. Zim frowned and cocked his head to the side, listening intently.

"No," he said, after a moment of thought.

"Hmm," said Dib, "that might be it, then." He dove back under water and kicked away, swimming in the direction he clearly believed the sound was coming from.

"Hey, what about your stupid earplugs?" Zim yelled, but the human couldn't hear underwater, obviously. With a groan, he dove back under and followed him.

Zim swam beneath him and waved, but the human's eyes were still scrunched shut against the water. How these creatures ever managed to move around when submerged without immediately drowning Zim would never understand. 

The human stopped, treading water. Zim frowned, then turned to see what he was looking at, but the water was clear. He broke the surface.

"Hey, worm boy, why did you st-" Zim froze.

On a craggy rise of stone in the center of the room, mirrored by dark water, sat a distinctly human shaped creature. Dib had been wrong in comparing it to Zim- this thing was human from it's waist up and cartoonish from the waist down. It was certainly reminiscent of an aquatic creature, certainly, but all wrong. It's tail was too short, and it was completely the opposite direction, bending the same direction as a humans legs would- distinctly mammalian, but the scales along its length made even that seem bizarre. It shimmered and beckoned with one hand, long, wet hair falling around it's perfectly symmetrical face and over it's shoulders.

Zim didn't trust that thing and further than he could throw it. 

"Alright, take your dumb photo," Zim said, still staring at the weird Thing. Its mouth was moving, but he couldn't hear a sound from it. Zim frowned. 

Beside him, Dib ducked into the water again, swimming toward it. 

"Do  _ not _ tell me you forgot your stupid earplugs," Zim groaned, even though Dib was now under water, "and the wretched thing has caught you in it's hypnotic spell. Wonderful." 

The Siren cast it's dark eyes toward him and smiled, and Zim sneered at it.

"Hey!" He called at the fish-facsimile, "That's my human! Not yours! You can't just go around stealing humans from people! It's rude!"

The Siren shrugged and flipped it's hair over its shoulder. Zim dove down and breached the water in an arced jump and then resurfaced.

"See? I've got a  _ proper _ aquatic structure, and thus a more legitimate claim over your planet's inhabitants," he snapped, "Don't make me shoot you. I will shoot you."

The Siren's eyes glimmered, appearing suddenly to be legitimately interested in him. It's mouth stopped moving. Dib stopped in place and looked around, confused.

"My earplugs!" he exclaimed, and Zim rolled his eyes. The Siren dove into the water.

"Take your picture, dummy, I want to get back before the ice creams are all gone," Zim said, watching the thing approach him with rising trepidation. He didn't like it, didn't want it near him.

"Right!" said Dib, fumbling for his camera. The Siren rose from the water, hair floating all around it, and this close, Zim could see its eyes glimmering and slit like a cats.

"Uh," he said, as it reached from the water to touch his face, "Okay."

"Zim, get out of the way so I can get a photo!"

"Do NOT capture my image, Dib stink! I will destroy it!" Zim snapped, as the Siren poked about to try and open his mouth and peer inside.

"I know that! That's why I'm telling you to move out of the way!"

"Its- I mean, it's making that kind of- oh, Merk, don't touch the antennae, are you insane?" Zim hissed, swatting it's hands away. It pulled back for a moment before moving to grab them again with more conviction, and he quickly backed up, out of its reach again. The Siren paused, as if surprised.

And then it's nose crinkled up, eyebrows knitting together in fury, and it's face split completely open in half, revealing hundreds of needle sharp teeth. Zim could only  _ assume _ it had made some kind of noise he couldn't hear, because Dib immediately went rigid, and  _ sank _ .

"Dib!" Zim heard himself cry, and he dove- or tried to, but the Siren had slammed into him, suddenly all test and claws and nonsense anatomy that absolutely infuriated him.

"Let go of me, abomination! You dare put your filthy hands on Zim!" Zim snapped out the legs of his PAK, fighting and grasping, churning the water wildly as he tried to shishkebab the thing and failed. 

Finally, he felt it grab at one of his arms, and took the opportunity to twist and grab it's wrist, before  _ chomping _ down on its forearm. It shrieked in the water and pulled away, giving him time to dive straight down and grab the sinking human, who was limp in the water.

Zim cursed in Merkin, spitting out bubbles and grabbed at the little fleshy mammal, pushing back up as quickly as he could before the boy's wretchedly evolved body let him drown. Zim felt claws grab his tail and yank him back. He didn't turn, but angled one PAK leg and stabbed it directly in the eye.

Yeah, he could hear the _ that _ scream. Zim couldn't help but split his face open into a sharp toothed triumphant grin over that as he rocketed back to the surface, forcing the humans head above the water again. Dib coughed and sputtered and gasped, suddenly flailing.

"Alright, cryptid trip over, we're leaving now!" Zim snapped.

"Gotcha!" Dib confirmed, being logical for once, and it took less than ten seconds for Zim to get sick of his miserably ineffective swimspeed.

"Fill your lungs, landworm," he snapped, and grabbed him, diving again to navigate the ripcurrents out of the cave.

They burst back out of the water and the human spat out a stream of seawater that made Zim stick out his tongue again in disgust. 

"Wow," Dib coughed, "Uh, I guess that uh, confirms that one. Definitely, uh, sirens definitely exist."

"Terrifically underwhelming," Zim grimaced, "Zim did not like this sirens disgustingly poorly designed fish tail."

"I thought it was pretty," Dib commented, pushing away the Merken so he could swim on his own again, paddling back toward shore.

"Dib has low standards," Zim commented, before looking back at the beach, his antennae snapping upward, "Hey!"

"What?" asked Dib, before he hit ground shallow enough to walk in and looked up, "Wow. Okay."

Someone had clearly stumbled upon their stuff, and it was now scattered about, though at least it appeared to all be there. Zims wheelchair, however, had clearly been run in doughnuts and was sitting several metres from the shore, tipped onto its side.

"Zim will  _ destroy _ the Earth creature who had the opportunity  _ gall _ -" he snapped, beginning a tirade.

"Wow, seriously, a wheelchair?" Dib scowled under his breath, "That's pretty low." 

He pulled himself onto the shore, and Zim threw both his palms on the rock and launched himself upward, catching himself on his PAK legs, skittering toward his chair like a giant lobster while he continued to rant and rave about what he was going to do to the idiot dumb enough to mess with his stuff.

"I mean, if you find them, you're welcome to give them a good right hook," said Dib, retrieving his glasses, "For now though, I've almost drowned so I think I'm good on swimming for the rest of the day. Did you want to go grab an ice cream before they're all out?"

Zim paused, picking his chair back up, and narrowed his eyes, "Yes. Zim _obviously_ wants his ice creams."


End file.
